# NCERT Solutions for Class 11 Geography Chapter 14 Movements of Ocean Water

Detailed, Step-by-Step NCERT Solutions for Class 11 Geography Chapter 14 Movements of Ocean Water Questions and Answers were solved by Expert Teachers as per NCERT (CBSE) Book guidelines covering each topic in chapter to ensure complete preparation.

## Movements of Ocean Water NCERT Solutions for Class 11 Geography Chapter 14

### Movements of Ocean Water Questions and Answers Class 11 Geography Chapter 14

Question 1.
Multiple Choice Questions :
(i) Upward and downward movement of ocean water is known n as the:
(a) tide
(b) current
(c) wave
(d) none of the above
(a) tide

(ii) Spring tides are caused :
(a) As a result of the moon and the sun pulling the earth gravitionally in the same direction
(b) As a result of the moon and sun pulling the earth gravitationally in the opposite direction
(c) Indention in the coastline
(d) None of the above
(a) As a result of the moon and the sun pulling the earth gravitationally in the same direction.

(iii) The distance between the earth and the moon is minimum when the moon is in
(a) Aphelion
(b) Perigee
(b) Perihelion
(d) Apogee
(b) Perigee.

(iv) The earth reaches its perihelion in :
(a) October
(b) September
(c) July
(d) January
(d) January.

Question 2.
(i) What are waves?
Waves are the oscillatory movement of water, where particles move up and down in a vertical plane.

(ii) Where do waves in the ocean get their energy from?
Waves are actually not the energy water as such. Wind provides energy to the waves. Wind causes waves to travel in the ocean and energy is released on the shorelines. The motion of the surface water seldom affects the stagnant deep bottom waters of the oceAnswer:As the wave approaches the beach, it slows down.

(iii) What are tides?
Tides are the periodic rise and tall in the level of water in oceans and seas caused by the differential attraction of the moon and the sun.

(iv) How are tides caused?
Tides are produced as gravitational interaction of the earth, moon and the sun. Twice a day, the sea level rises and falls. The rise of sea level is called the flood tide and the fall is called the ebb tide.

(v) How are tides related to navigation?
Since the tides are caused by the earth-moon-sun positions, which are known accurately, the tides can be predicted well in advance This helps the navigators and fishermen plan their activities. Tidal flows are of profound importance in navigation. Tidal heights near the rivers prevent ships and boats from entering into the harbour.

Question 3.
(i) How do currents affect the temperature? How do they affect the temperature of coastal areas in the N.W. Europe?
The ocean current affects the temperature. The west coasts of the continents in tropical and sub-tropical latitudes (except close to the equator) are bordered by cool waters.

Their average temperatures are relatively low with narrow diurnal and annual ranges. There is fog, but generally the areas are arid. West coasts of the continents in middle and higher latitudes are bordered by warm waters which cause a distinct marine climate.

They are characterised by cool summers and relatively mild winters with a narrow annual range of temperatures. Warm currents flow parallel to east coasts of the continents in tropical and sub-tropical latitudes. This results in warm and rainy climates. These areas lie in the western margins of the sub-tropical anticyclones.

Effect of oceanic currents on the temperature in Europe :
The Antilles current is the western extension of the North Equatorial current. It flows along the northern side of the Greater Antilles. The Gulf Stream current begins from the Florida Strait and flows northward and eastward along the sea coast of United States. Here, heavy fogs form

along the boundary where the warm Gulf Stream meets the cold Labrador current. The mixing helps the planktons, the micro-nutrients of the fish, to flourish.

The warm Gulf Stream current is responsible for the mild climate that prevails throughout the north-western Europe. Even in winter, Norwegian ports along the Atlantic are ice-free most of the time. In contrast, a cold ocean current flowing equatorward along the west coast of the continents brings relatively cool summer and cold winter.

(ii) What are the causes of currents?